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Comparative study of negative electron affinity GaAs nanowire photocathodes with Cs/O and with Cs/NF 3 from first‐principles
Author(s) -
Diao Yu,
Liu Lei,
Xia Sihao
Publication year - 2019
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.4780
Subject(s) - nanowire , electron affinity (data page) , electron , chemistry , materials science , atomic physics , nanotechnology , physics , molecule , nuclear physics , organic chemistry
Summary We perform a detailed comparative study of Cs/O and Cs/NF 3 activation mechanism of negative electron affinity (NEA) GaAs nanowire photocathodes through first‐principles calculations based on density functional theory (DFT). The adsorption energy, Mulliken charge distribution, work function, electron affinity, and dipole moment are analyzed. Results show that the stability of Cs/NF 3 co‐adsorption nanowire surface is stronger than that of the Cs/O model. The incorporation of O or NF 3 on Cs‐covered nanowire surfaces leads to a sharper decline of surface work function. The NEA states can be attained with both O 2 and NF 3 . However, during the Cs/O activation process, it needs to strictly control the Cs/O ratio to achieve the maximum photoemission properties of cathode. Moreover, the work function variation of GaAs nanowire photocathodes activated with Cs, O, and NF 3 can be explained by the dipole moment model. This work is expected to provide a theoretical guide for improving Cs/O and Cs/NF 3 activation procedure for NEA GaAs nanowire photocathodes.